OFDMA Tone Plan for 802.11ax WLAN
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Solution Overview
Problem
The existing 802.11ax wireless LAN system faces challenges in enhancing throughput and robustness in outdoor environments, particularly with inter-symbol interference, and requires an efficient tone plan for OFDMA schemes that maximizes compatibility with legacy systems and optimizes pilot tone placement.
Innovation Solution
The proposed solution involves a station apparatus that employs FEC encoding, constellation mapping, and inverse discrete Fourier transform for data transmission, using OFDMA with tone-units of 26, 52, and 242 tones, and strategically placing pilot tones within these units to ensure symmetry and compatibility with legacy systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDMA scheme is implemented with multiple tone-units (26, 52, 242 tones) to improve spectrum efficiency and area throughput, then system productivity increases, but device complexity increases due to the need for sophisticated tone plan management and pilot tone placement optimization
Solution Approach 1:
The frequency spectrum is segmented into multiple tone-units with different sizes (26, 52, and 242 tones) that can be independently allocated to different users. This segmentation enables flexible resource allocation while maintaining manageable complexity through standardized unit definitions and placement rules for each tone-unit type.
2Measurement precision
If pilot tones are strategically placed within tone-units to maximize compatibility with legacy systems and optimize estimation accuracy, then measurement precision improves, but device complexity increases due to the need for sophisticated pilot mapping functions
Solution Approach 1:
Different pilot tone placement strategies are applied locally to different tone-unit types (26-tone, 52-tone, 242-tone units) based on their specific characteristics and requirements. Each tone-unit has optimized pilot positions that maximize estimation accuracy for that particular unit size while maintaining overall system compatibility through standardized interfaces.
Data Source
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Figure 3(a)~3(d)
AI summary
Disclosed is a data transmission method of a station (STA) apparatus in a wireless local area network (WLAN) system. The data transmission method according to an embodiment of the present invention includes FEC-encoding transmission data, constellation-mapping the transmission data, inserting a pilot tone into the transmission data, performing inverse discrete Fourier transform (IDFT) on the transmission data, and up-converting the transmission data and transmitting a transmission signal. If an orthogonal frequency division multiple access (OFDMA) scheme is applied to the transmission signal, the transmission signal comprises at least one tone-unit which is a basis for subcarrier allocation of the OFDMA scheme.